Site Description The southern portal of Pwll Du tunnel (nprn 85830), carrying Hill's Tramroad (nprn 85860). The tunnel was probably made from the northwards extension to Pwll Du in 1815 of a mining level in the hillside north of Blaenavon Ironworks (nprn 34134). In July 2000, the portal was half buried and blocked but the top of the arch of white-brick voussoirs was visible.
RCAHMW, 06 November 2007.